advice on painting mdf

[tsb]

Hi, first of all 'what a great forum'. Have only been a member for a few days but very impressed with answers given to questions. I've just built a large extension on my house(never built anything before and has taken me 18 months, but saved me probably £20k) and now going to have a go at building the kitchen. Can't bring myself to pay £4000 from B&Q. Planning on a faceframe in oak and a door in mdf and painted cream. The problem is that the cut edge of mdf can be quite rough and I want a flat smooth finish. Whats the secret in painting mdf so that you can't tell its mdf. Also I'm intending on using butt hinges. Will these hinges be ok with mdf. Any advice would be great

 

[George_N]

I Treat cut edges of MDF with diluted PVA glue approx. (5 parts glue to 1 part water). Let it dry and sand to 320 grit sandpaper. Make sure the edges are well sealed. I have sprayed my MDF frame and panel kitchen cabinet doors with water-based paint, primer undercoat, top coat, and sealed with Ronseal diamond hard floor varnish. I Have used a B&Q HVLP sprayer (discontinued now unfortunately). The edges probably need an extra coat or two at the undercoat stage to ensure good coverage. I have also tried wallpaper paste and plasterboard jointing compound to seal edges but these are both very messy and don't work as well as the PVA in my experience. You don't have to spray the paint to get a good result. Try searching the forum for posts by JasonB (I think). Ho gets great looking resulys by applying the paint with a roller and laying off with a good quality brush. I seem to recall that he also uses acrylic sanding sealer to seal cut edges.

 

[jasonB]

Actually I use acrylic primer/undercoat (Dulux trade) on the cut edges which have been sanded to 120g beforehand. After the first coat cut back with 320g silicon carbide paper. Oil based undercoat and oil based eggshell after that.

One thing that will make a lot of difference is the quality of your MDF. THe sheds and general timber merchants sell "contract" grade boards which are quite "fluffy" and the edge plecks up when painted. Go to a decent panel supplier and buy MR (moisture resistant) MDF, I use Caber but Medite is also a good make.

Screwing into the edge of MDF is not ideal particularly in a kitchen where the doors will get a lot of use. If you do go with butts then use 22mm board and long thin 3.5x30 screws into 2.5mm pilot holes but the layers may still split. Better to go for concealed (blum) thype hinges with suitable arms and mounting plates for inset doors in face frames.

Jason

 

[tsb]

Thanks for the replies. Had thought as much about the problem with a butt hinge going into mdf. I just think ,personally, a stainless steel butt hinge looks more expensive than hidden hinges. The design of the door is a take on the shaker door ,with 4 pieces of a frame and a panel inside, so if the hinge side of the door was made out of beech, so it could take some screws, and the rest of the door made from mdf, would that work and once painted would it look ok

 

[jasonB]

Should work, may be a slight risk of different movement between beech/MDF causing paint to crack but if its well kiln dried will be ok.

Jason

 

[mailee]

I have made doors in mdf and used butt hinges. I drill holes for dowels where the screws will go and then glue them into the door edge. Pilot drilll the dowel and then add the hinges. This seems to work quite well as long as the dowels are deep enough. :wink:

 

[tsb]

Would never have thought of doing that!! Will give that a go , Thanks

 

[Anonymous]

Hi team

This is a copy of a reply I made on another forum regarding the paint of MDF

Painting MDF
With my projects I all ways use MR mdf ( moisture resisting) no mater what the project is, it is more dense which in turn will go a long way in giving you a better finish. I always seal plan mdf with a pigmented precatalyst lacquer and is applied by spray gun and is a professional product and not available from the big sheds. But if you don’t have the ways or the means with the above you can give the following a go and I think you will find it work extremely well, its all in the preparation.

• Plane all cut edges and I mean all cut edges even the edges you will not see, this process together with the sanding will go some way to help seal the cut edges as well as giving a more professional job.
• Fine sand (180 grit ) the cut edges at the same time remove the sharp edges.
• Thin 50% pva water proof wood glue with water and apply a thin and even coating to all cut edges and allow to dry fully, the adhesive will help give a water proof seal and cut down on the number of coats of paint.
• Once fully dry you can either apply iron on edging to the prepared cut edges or you can de-nib with a fine sand paper (320 grit) and apply your first coat of oil based primer to the cut edges only.
• If you want to go down the path of using iron on edging then do not de-nib the cut edges. Apply the edging making sure all the edges are well and truly fixed. It doesn’t mater about marking or burning the edging because when you have done all edges you will paint the edges once you have fine sanded the edging.
• Which ever path you want to go down at this stage you apply your first coat water based or oil based primer paint to all surfaces but applying by 100mm foam roller.
• De- nib between coats (320 grit) and apply finishing coats.

By going the extra mile on the edges you will stop the mdf act like a sponge and it is the edges that will let the side down and been the first part to allow the ingress of water.

You can get white iron on edging in 22, 30, and 50mm widths so even if you have rounded over the edges you can still apply edging. But to do a first class job that will stand head and shoulders above the rest, plane and fine sand all cut edges and seal with thin pva water proof glue.

Using a foam roller and making a little paint go a long way will give you a flat smooth finish flat finish without bush marks.

In the end you will have a project looking like a job in the town for all your hard work.

 

[mailee]

If you do go the spraying route, you could use the system I use which is two coats of a good MDF primer. (I use Johnstones) applied with a foam roller. Then sand with 320 grit paper. Two full coats of Wickes high gloss white water based. Allow two days to harden and then flat back with 800 wet n dry and then machine polish with a fine rubbing compound. this is the result on the sheds MDF.

I will add that as Bespoke has suggested to seal the edges with PVA and water though as these do soak up a lot.

 

[Anonymous]

Just to add one thing. We see and read a lot about MDF primer I forgot to mention that I use a no frills attached water based primer /undercoat as the very first coat after sealing the edges and the paint I use is Wickes or Leyland applied by roller and paint brush and I hear you ask well its simple you are going to remove due to sanding nearly 75% so why use you best paint for this first stage ?

 

[kafkaian]

I Treat cut edges of MDF with diluted PVA glue approx. (5 parts glue to 1 part water)....

I'm going to try this method today. Generally I have always painted with primer, waited for the fibres to rise, sand and fill with car body filler (cheaper than wood filler), sand and repeat before applying undercoats and topcoats. This generally works very well but is time consuming.

As for PVA, do you worry whether or not this is the waterproof variety (which I have plenty of)?

 

[George_N]

I Treat cut edges of MDF with diluted PVA glue approx. (5 parts glue to 1 part water)....

I'm going to try this method today. Generally I have always painted with primer, waited for the fibres to rise, sand and fill with car body filler (cheaper than wood filler), sand and repeat before applying undercoats and topcoats. This generally works very well but is time consuming.

As for PVA, do you worry whether or not this is the waterproof variety (which I have plenty of)?

I use waterproof PVA because A) that is what I've got and B) because I have been painting with water based paints.

 

[kafkaian]

I Treat cut edges of MDF with diluted PVA glue approx. (5 parts glue to 1 part water)....

I'm going to try this method today. Generally I have always painted with primer, waited for the fibres to rise, sand and fill with car body filler (cheaper than wood filler), sand and repeat before applying undercoats and topcoats. This generally works very well but is time consuming.

As for PVA, do you worry whether or not this is the waterproof variety (which I have plenty of)?

I use waterproof PVA because A) that is what I've got and B) because I have been painting with water based paints.

I'm sure the primer on top will cope anyway. Thanks George

 

[Mark.R]

But can you get Melamine faced MDF? I ask this because my kitchen scratch build project will be starting in the summer and if this was available it would save so much time and effort.

Please let us know who supplies this.

Thanks.

Mark.r

 

[Anonymous]

But can you get Melamine faced MDF? I ask this because my kitchen scratch build project will be starting in the summer and if this was available it would save so much time and effort.

Please let us know who supplies this.

Thanks.

Mark.r

Well I bought some from the fleabay. Not that impressed with it really, my fag papers are thicker than the Melamine on it. Perhaps a proper supplier will do a better type?

 

[Larni]

I am looking for some advice on the best possible way to apply paint to small MDF blocks that I am going to mount photos on. If anyone has any suggestions it would be greatly appreciated.

 

[miles_hot]

Thanks for the replies. Had thought as much about the problem with a butt hinge going into mdf. I just think ,personally, a stainless steel butt hinge looks more expensive than hidden hinges. The design of the door is a take on the shaker door ,with 4 pieces of a frame and a panel inside, so if the hinge side of the door was made out of beech, so it could take some screws, and the rest of the door made from mdf, would that work and once painted would it look ok

Just a thought - if you're going to use Beach on one side of the door would you consider using beach to build a frame (consistent grain etc) and then maybe ply for the centre panel - assuming you're not having a raised element?

Other than that - great advice on the rest of the thread and some awesome results!

Miles

 

[wizer]

Larni: Welcome to the forum. Did you read this thread? I just re-read it (originating from late 2007) and it contains about the most comprehensive advise for painting MDF that you can get. Is there a specific part you are confused about? In short: Sand edges to 120g, Seal all faces and edges with PVA/Water, Undercoat with primer, sand lightly to 320g, apply topcoat. Use a mini roller.

There's your formula. Post some pics when it's done

 

[Krysstel]

This is an old thread but I'll pick it up again since it's relavant for what I'm about to do.

I've read elsewhere that MR-MDF is far better than standard MDF, especially hardness, surface quality and ease of machining.

But what about glueing and painting ?
Does it take paint as well as standard MDF ? Do you need to seal as well ?
I'm considering using two layers of MR for a router table. Will I have any problems glueing them together, surface to surface ? (I'm not planing to paint the router table - that's another project !)

 

[the_g_ster]

Hi,

Once you've used the MR stuff you won't go back to the normal stuff. IT machines well, holds better and isn't fluffy.

It glues fine, it takes finish very well, I have had some good results spraying, get out there and buy some.